The present invention relates to vision systems, and more specifically, to a vision system coupled to a motion controller, the motion controller providing motion data used for generating an image acquisition trigger signal.
In many applications, machine vision or image processing analysis is used to inspect or locate an object. For example, in manufacturing applications, machine vision analysis may be used to detect defects in a manufactured object by acquiring images of the object and using various types of image processing algorithms to analyze the images. As an example, a system to manufacture an object such as a memory disk may use machine vision to examine the object in order to detect manufacturing defects, and ensure that the object is marked or assembled properly.
In such machine vision systems, an encoder is often used to communicate object position to the vision system in order to generate trigger signals at calculated times and to schedule the generation of digital outputs. The trigger signals are used to acquire one or more images of the object in the field of view as it moves in front of the vision system, and the digital outputs may be used for triggering a reject mechanism, for example. FIG. 1 shows an illustrative machine vision system 20 adapted to acquire one or more images 22 of a memory disk 24. Conveyor 28 transports the disks 24 to cause relative movement between the disks 24 and the field of view 30 of imaging device 32. Motion of the conveyor 28 is tracked by one or more encoders 36. The encoder 36 sends signals over link 40 to a controller 42 (e.g., a processor device), which uses the encoder signals to calculate disk position, and to generate a trigger signal over link 44 at calculated times to the imaging device 32 to acquire one or more images of the disk 24 in the field of view. If the disk 24 is defective, the imaging device 32 and/or the controller 42 may be programmed to send a signal over link 46 to a reject actuator 48 to remove the defective disk 50 from the conveyor 28 as shown.
In some cases, however, encoders can be troublesome and undesirable due to their inaccuracies, noise immunity issues, and reliability issues. Accordingly, in some cases, removing the need for a separate encoder to provide position data to the imaging device would improve overall performance for the machine vision system, reduce points of failure, and increase efficiencies for the vision system user.